[ViewVC] Diff of: cvs/libev/ev.html

Comparing libev/ev.html (file contents):
Revision 1.41 by root, Sat Nov 24 10:15:16 2007 UTC vs.
Revision 1.76 by root, Sun Dec 9 19:47:29 2007 UTC

 <head>
 	<title>libev</title>
 	<meta name="description" content="Pod documentation for libev" />
 	<meta name="inputfile" content="&lt;standard input&gt;" />
 	<meta name="outputfile" content="&lt;standard output&gt;" />
-	<meta name="created" content="Sat Nov 24 11:15:15 2007" />
+	<meta name="created" content="Sun Dec  9 20:47:27 2007" />
 	<meta name="generator" content="Pod::Xhtml 1.57" />
 <link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
 <body>
 <div class="pod">
 <!-- INDEX START -->
 <h3 id="TOP">Index</h3>
 <ul><li><a href="#NAME">NAME</a></li>
 <li><a href="#SYNOPSIS">SYNOPSIS</a></li>
+<li><a href="#EXAMPLE_PROGRAM">EXAMPLE PROGRAM</a></li>
 <li><a href="#DESCRIPTION">DESCRIPTION</a></li>
 <li><a href="#FEATURES">FEATURES</a></li>
 <li><a href="#CONVENTIONS">CONVENTIONS</a></li>
 <li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
 <li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
 <li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>
 <li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>
-<ul><li><a href="#SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</a></li>
+<ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li>
 <li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
 </ul>
 </li>
 <li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
-<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li>
+<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li>
-<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li>
+<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li>
-<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li>
+<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li>
-<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li>
+<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li>
-<li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li>
+<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li>
+<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li>
-<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li>
+<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li>
-<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li>
+<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a></li>
-<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</a></li>
+<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li>
+<li><a href="#code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</a></li>
 </ul>
 </li>
 <li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
 <li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
 <li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
+<li><a href="#MACRO_MAGIC">MACRO MAGIC</a></li>
 <li><a href="#EMBEDDING">EMBEDDING</a>
 <ul><li><a href="#FILESETS">FILESETS</a>
 <ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>
 <li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>
 <li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>
 </li>
 <li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>
 <li><a href="#EXAMPLES">EXAMPLES</a></li>
 </ul>
 </li>
+<li><a href="#COMPLEXITIES">COMPLEXITIES</a></li>
 <li><a href="#AUTHOR">AUTHOR</a>
 </li>
 </ul><hr />
 <!-- INDEX END -->
-<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="NAME">NAME</h1>
 <div id="NAME_CONTENT">
 <p>libev - a high performance full-featured event loop written in C</p>
 </div>
-<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="SYNOPSIS">SYNOPSIS</h1>
 <div id="SYNOPSIS_CONTENT">
 <pre>  #include &lt;ev.h&gt;
 </pre>
 </div>
-<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1>
+<div id="EXAMPLE_PROGRAM_CONTENT">
+<pre>  #include &lt;ev.h&gt;
+  ev_io stdin_watcher;
+  ev_timer timeout_watcher;
+  /* called when data readable on stdin */
+  static void
+  stdin_cb (EV_P_ struct ev_io *w, int revents)
+  {
+    /* puts (&quot;stdin ready&quot;); */
+    ev_io_stop (EV_A_ w); /* just a syntax example */
+    ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
+  }
+  static void
+  timeout_cb (EV_P_ struct ev_timer *w, int revents)
+  {
+    /* puts (&quot;timeout&quot;); */
+    ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
+  }
+  int
+  main (void)
+  {
+    struct ev_loop *loop = ev_default_loop (0);
+    /* initialise an io watcher, then start it */
+    ev_io_init (&amp;stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
+    ev_io_start (loop, &amp;stdin_watcher);
+    /* simple non-repeating 5.5 second timeout */
+    ev_timer_init (&amp;timeout_watcher, timeout_cb, 5.5, 0.);
+    ev_timer_start (loop, &amp;timeout_watcher);
+    /* loop till timeout or data ready */
+    ev_loop (loop, 0);
+    return 0;
+  }
+</pre>
+</div>
+<h1 id="DESCRIPTION">DESCRIPTION</h1>
 <div id="DESCRIPTION_CONTENT">
+<p>The newest version of this document is also available as a html-formatted
+web page you might find easier to navigate when reading it for the first
+time: <a href="http://cvs.schmorp.de/libev/ev.html">http://cvs.schmorp.de/libev/ev.html</a>.</p>
 <p>Libev is an event loop: you register interest in certain events (such as a
 file descriptor being readable or a timeout occuring), and it will manage
 these event sources and provide your program with events.</p>
 <p>To do this, it must take more or less complete control over your process
 (or thread) by executing the <i>event loop</i> handler, and will then
 watchers</i>, which are relatively small C structures you initialise with the
 details of the event, and then hand it over to libev by <i>starting</i> the
 watcher.</p>
 </div>
-<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="FEATURES">FEATURES</h1>
 <div id="FEATURES_CONTENT">
-<p>Libev supports select, poll, the linux-specific epoll and the bsd-specific
+<p>Libev supports <code>select</code>, <code>poll</code>, the Linux-specific <code>epoll</code>, the
-kqueue mechanisms for file descriptor events, relative timers, absolute
+BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms
-timers with customised rescheduling, signal events, process status change
+for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface
-events (related to SIGCHLD), and event watchers dealing with the event
+(for <code>ev_stat</code>), relative timers (<code>ev_timer</code>), absolute timers
-loop mechanism itself (idle, prepare and check watchers). It also is quite
+with customised rescheduling (<code>ev_periodic</code>), synchronous signals
+(<code>ev_signal</code>), process status change events (<code>ev_child</code>), and event
+watchers dealing with the event loop mechanism itself (<code>ev_idle</code>,
+<code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as
+file watchers (<code>ev_stat</code>) and even limited support for fork events
+(<code>ev_fork</code>).</p>
+<p>It also is quite fast (see this
-fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing
+<a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent
-it to libevent for example).</p>
+for example).</p>
 </div>
-<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="CONVENTIONS">CONVENTIONS</h1>
 <div id="CONVENTIONS_CONTENT">
-<p>Libev is very configurable. In this manual the default configuration
+<p>Libev is very configurable. In this manual the default configuration will
-will be described, which supports multiple event loops. For more info
+be described, which supports multiple event loops. For more info about
-about various configuration options please have a look at the file
+various configuration options please have a look at <strong>EMBED</strong> section in
-<cite>README.embed</cite> in the libev distribution. If libev was configured without
+this manual. If libev was configured without support for multiple event
-support for multiple event loops, then all functions taking an initial
+loops, then all functions taking an initial argument of name <code>loop</code>
-argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>)
+(which is always of type <code>struct ev_loop *</code>) will not have this argument.</p>
-will not have this argument.</p>
 </div>
-<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
 <div id="TIME_REPRESENTATION_CONTENT">
 <p>Libev represents time as a single floating point number, representing the
 (fractional) number of seconds since the (POSIX) epoch (somewhere near
 the beginning of 1970, details are complicated, don't ask). This type is
 called <code>ev_tstamp</code>, which is what you should use too. It usually aliases
 to the <code>double</code> type in C, and when you need to do any calculations on
 it, you should treat it as such.</p>
 </div>
-<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
 <div id="GLOBAL_FUNCTIONS_CONTENT">
 <p>These functions can be called anytime, even before initialising the
 library in any way.</p>
 <dl>
 	<dt>ev_tstamp ev_time ()</dt>
 you actually want to know.</p>
 	</dd>
 	<dt>int ev_version_major ()</dt>
 	<dt>int ev_version_minor ()</dt>
 	<dd>
-		<p>You can find out the major and minor version numbers of the library
+		<p>You can find out the major and minor ABI version numbers of the library
 you linked against by calling the functions <code>ev_version_major</code> and
 <code>ev_version_minor</code>. If you want, you can compare against the global
 symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the
 version of the library your program was compiled against.</p>
+		<p>These version numbers refer to the ABI version of the library, not the
+release version.</p>
 		<p>Usually, it's a good idea to terminate if the major versions mismatch,
-as this indicates an incompatible change.  Minor versions are usually
+as this indicates an incompatible change. Minor versions are usually
 compatible to older versions, so a larger minor version alone is usually
 not a problem.</p>
-		<p>Example: make sure we haven't accidentally been linked against the wrong
+		<p>Example: Make sure we haven't accidentally been linked against the wrong
-version:</p>
+version.</p>
 <pre>  assert ((&quot;libev version mismatch&quot;,
            ev_version_major () == EV_VERSION_MAJOR
            &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR));
 </pre>
 recommended ones.</p>
 		<p>See the description of <code>ev_embed</code> watchers for more info.</p>
 	</dd>
 	<dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt>
 	<dd>
-		<p>Sets the allocation function to use (the prototype is similar to the
+		<p>Sets the allocation function to use (the prototype is similar - the
-realloc C function, the semantics are identical). It is used to allocate
+semantics is identical - to the realloc C function). It is used to
-and free memory (no surprises here). If it returns zero when memory
+allocate and free memory (no surprises here). If it returns zero when
-needs to be allocated, the library might abort or take some potentially
+memory needs to be allocated, the library might abort or take some
-destructive action. The default is your system realloc function.</p>
+potentially destructive action. The default is your system realloc
+function.</p>
 		<p>You could override this function in high-availability programs to, say,
 free some memory if it cannot allocate memory, to use a special allocator,
 or even to sleep a while and retry until some memory is available.</p>
-		<p>Example: replace the libev allocator with one that waits a bit and then
+		<p>Example: Replace the libev allocator with one that waits a bit and then
-retries: better than mine).</p>
+retries).</p>
 <pre>   static void *
-   persistent_realloc (void *ptr, long size)
+   persistent_realloc (void *ptr, size_t size)
    {
      for (;;)
        {
          void *newptr = realloc (ptr, size);
 indicating the system call or subsystem causing the problem. If this
 callback is set, then libev will expect it to remedy the sitution, no
 matter what, when it returns. That is, libev will generally retry the
 requested operation, or, if the condition doesn't go away, do bad stuff
 (such as abort).</p>
-		<p>Example: do the same thing as libev does internally:</p>
+		<p>Example: This is basically the same thing that libev does internally, too.</p>
 <pre>   static void
    fatal_error (const char *msg)
    {
      perror (msg);
      abort ();
 </pre>
 	</dd>
 </dl>
 </div>
-<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1>
 <div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
 <p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two
 types of such loops, the <i>default</i> loop, which supports signals and child
 events, and dynamically created loops which do not.</p>
 <p>If you use threads, a common model is to run the default event loop
 <code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will
 override the flags completely if it is found in the environment. This is
 useful to try out specific backends to test their performance, or to work
 around bugs.</p>
 				</dd>
+				<dt><code>EVFLAG_FORKCHECK</code></dt>
+				<dd>
+					<p>Instead of calling <code>ev_default_fork</code> or <code>ev_loop_fork</code> manually after
+a fork, you can also make libev check for a fork in each iteration by
+enabling this flag.</p>
+					<p>This works by calling <code>getpid ()</code> on every iteration of the loop,
+and thus this might slow down your event loop if you do a lot of loop
+iterations and little real work, but is usually not noticeable (on my
+Linux system for example, <code>getpid</code> is actually a simple 5-insn sequence
+without a syscall and thus <i>very</i> fast, but my Linux system also has
+<code>pthread_atfork</code> which is even faster).</p>
+					<p>The big advantage of this flag is that you can forget about fork (and
+forget about forgetting to tell libev about forking) when you use this
+flag.</p>
+					<p>This flag setting cannot be overriden or specified in the <code>LIBEV_FLAGS</code>
+environment variable.</p>
+				</dd>
 				<dt><code>EVBACKEND_SELECT</code>  (value 1, portable select backend)</dt>
 				<dd>
 					<p>This is your standard select(2) backend. Not <i>completely</i> standard, as
 libev tries to roll its own fd_set with no limits on the number of fds,
 but if that fails, expect a fairly low limit on the number of fds when
 	<dd>
 		<p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is
 always distinct from the default loop. Unlike the default loop, it cannot
 handle signal and child watchers, and attempts to do so will be greeted by
 undefined behaviour (or a failed assertion if assertions are enabled).</p>
-		<p>Example: try to create a event loop that uses epoll and nothing else.</p>
+		<p>Example: Try to create a event loop that uses epoll and nothing else.</p>
 <pre>  struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
   if (!epoller)
     fatal (&quot;no epoll found here, maybe it hides under your chair&quot;);
 </pre>
 	<dt>ev_loop_fork (loop)</dt>
 	<dd>
 		<p>Like <code>ev_default_fork</code>, but acts on an event loop created by
 <code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop
 after fork, and how you do this is entirely your own problem.</p>
+	</dd>
+	<dt>unsigned int ev_loop_count (loop)</dt>
+	<dd>
+		<p>Returns the count of loop iterations for the loop, which is identical to
+the number of times libev did poll for new events. It starts at <code>0</code> and
+happily wraps around with enough iterations.</p>
+		<p>This value can sometimes be useful as a generation counter of sorts (it
+&quot;ticks&quot; the number of loop iterations), as it roughly corresponds with
+<code>ev_prepare</code> and <code>ev_check</code> calls.</p>
 	</dd>
 	<dt>unsigned int ev_backend (loop)</dt>
 	<dd>
 		<p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in
 use.</p>
 one iteration of the loop. This is useful if you are waiting for some
 external event in conjunction with something not expressible using other
 libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is
 usually a better approach for this kind of thing.</p>
 		<p>Here are the gory details of what <code>ev_loop</code> does:</p>
+<pre>   - Before the first iteration, call any pending watchers.
-<pre>   * If there are no active watchers (reference count is zero), return.
+   * If there are no active watchers (reference count is zero), return.
-   - Queue prepare watchers and then call all outstanding watchers.
+   - Queue all prepare watchers and then call all outstanding watchers.
    - If we have been forked, recreate the kernel state.
    - Update the kernel state with all outstanding changes.
    - Update the &quot;event loop time&quot;.
    - Calculate for how long to block.
    - Block the process, waiting for any events.
      be handled here by queueing them when their watcher gets executed.
    - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
      were used, return, otherwise continue with step *.
 </pre>
-		<p>Example: queue some jobs and then loop until no events are outsanding
+		<p>Example: Queue some jobs and then loop until no events are outsanding
 anymore.</p>
 <pre>   ... queue jobs here, make sure they register event watchers as long
    ... as they still have work to do (even an idle watcher will do..)
    ev_loop (my_loop, 0);
    ... jobs done. yeah!
 example, libev itself uses this for its internal signal pipe: It is not
 visible to the libev user and should not keep <code>ev_loop</code> from exiting if
 no event watchers registered by it are active. It is also an excellent
 way to do this for generic recurring timers or from within third-party
 libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>
-		<p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code>
+		<p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
 running when nothing else is active.</p>
-<pre>  struct dv_signal exitsig;
+<pre>  struct ev_signal exitsig;
   ev_signal_init (&amp;exitsig, sig_cb, SIGINT);
-  ev_signal_start (myloop, &amp;exitsig);
+  ev_signal_start (loop, &amp;exitsig);
-  evf_unref (myloop);
+  evf_unref (loop);
 </pre>
-		<p>Example: for some weird reason, unregister the above signal handler again.</p>
+		<p>Example: For some weird reason, unregister the above signal handler again.</p>
-<pre>  ev_ref (myloop);
+<pre>  ev_ref (loop);
-  ev_signal_stop (myloop, &amp;exitsig);
+  ev_signal_stop (loop, &amp;exitsig);
 </pre>
 	</dd>
 </dl>
 </div>
-<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1>
 <div id="ANATOMY_OF_A_WATCHER_CONTENT">
 <p>A watcher is a structure that you create and register to record your
 interest in some event. For instance, if you want to wait for STDIN to
 become readable, you would create an <code>ev_io</code> watcher for that:</p>
 <pre>  static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
 	</dd>
 	<dt><code>EV_CHILD</code></dt>
 	<dd>
 		<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>
 	</dd>
+	<dt><code>EV_STAT</code></dt>
+	<dd>
+		<p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p>
+	</dd>
 	<dt><code>EV_IDLE</code></dt>
 	<dd>
 		<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>
 	</dd>
 	<dt><code>EV_PREPARE</code></dt>
 <code>ev_loop</code> has gathered them, but before it invokes any callbacks for any
 received events. Callbacks of both watcher types can start and stop as
 many watchers as they want, and all of them will be taken into account
 (for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep
 <code>ev_loop</code> from blocking).</p>
+	</dd>
+	<dt><code>EV_EMBED</code></dt>
+	<dd>
+		<p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p>
+	</dd>
+	<dt><code>EV_FORK</code></dt>
+	<dd>
+		<p>The event loop has been resumed in the child process after fork (see
+<code>ev_fork</code>).</p>
 	</dd>
 	<dt><code>EV_ERROR</code></dt>
 	<dd>
 		<p>An unspecified error has occured, the watcher has been stopped. This might
 happen because the watcher could not be properly started because libev
 programs, though, so beware.</p>
 	</dd>
 </dl>
 </div>
-<h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2>
+<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
-<div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2">
+<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
 <p>In the following description, <code>TYPE</code> stands for the watcher type,
 e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
 <dl>
 	<dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
 	<dd>
 the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
 type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
 which rolls both calls into one.</p>
 		<p>You can reinitialise a watcher at any time as long as it has been stopped
 (or never started) and there are no pending events outstanding.</p>
-		<p>The callbakc is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher,
+		<p>The callback is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher,
 int revents)</code>.</p>
 	</dd>
 	<dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
 	<dd>
 		<p>This macro initialises the type-specific parts of a watcher. You need to
 	<dt>bool ev_is_pending (ev_TYPE *watcher)</dt>
 	<dd>
 		<p>Returns a true value iff the watcher is pending, (i.e. it has outstanding
 events but its callback has not yet been invoked). As long as a watcher
 is pending (but not active) you must not call an init function on it (but
-<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to
+<code>ev_TYPE_set</code> is safe), you must not change its priority, and you must
-libev (e.g. you cnanot <code>free ()</code> it).</p>
+make sure the watcher is available to libev (e.g. you cannot <code>free ()</code>
+it).</p>
 	</dd>
-	<dt>callback = ev_cb (ev_TYPE *watcher)</dt>
+	<dt>callback ev_cb (ev_TYPE *watcher)</dt>
 	<dd>
 		<p>Returns the callback currently set on the watcher.</p>
 	</dd>
 	<dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
 	<dd>
 		<p>Change the callback. You can change the callback at virtually any time
 (modulo threads).</p>
+	</dd>
+	<dt>ev_set_priority (ev_TYPE *watcher, priority)</dt>
+	<dt>int ev_priority (ev_TYPE *watcher)</dt>
+	<dd>
+		<p>Set and query the priority of the watcher. The priority is a small
+integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code>
+(default: <code>-2</code>). Pending watchers with higher priority will be invoked
+before watchers with lower priority, but priority will not keep watchers
+from being executed (except for <code>ev_idle</code> watchers).</p>
+		<p>This means that priorities are <i>only</i> used for ordering callback
+invocation after new events have been received. This is useful, for
+example, to reduce latency after idling, or more often, to bind two
+watchers on the same event and make sure one is called first.</p>
+		<p>If you need to suppress invocation when higher priority events are pending
+you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p>
+		<p>You <i>must not</i> change the priority of a watcher as long as it is active or
+pending.</p>
+		<p>The default priority used by watchers when no priority has been set is
+always <code>0</code>, which is supposed to not be too high and not be too low :).</p>
+		<p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is
+fine, as long as you do not mind that the priority value you query might
+or might not have been adjusted to be within valid range.</p>
+	</dd>
+	<dt>ev_invoke (loop, ev_TYPE *watcher, int revents)</dt>
+	<dd>
+		<p>Invoke the <code>watcher</code> with the given <code>loop</code> and <code>revents</code>. Neither
+<code>loop</code> nor <code>revents</code> need to be valid as long as the watcher callback
+can deal with that fact.</p>
+	</dd>
+	<dt>int ev_clear_pending (loop, ev_TYPE *watcher)</dt>
+	<dd>
+		<p>If the watcher is pending, this function returns clears its pending status
+and returns its <code>revents</code> bitset (as if its callback was invoked). If the
+watcher isn't pending it does nothing and returns <code>0</code>.</p>
 	</dd>
 </dl>
     struct my_io *w = (struct my_io *)w_;
     ...
   }
 </pre>
-<p>More interesting and less C-conformant ways of catsing your callback type
+<p>More interesting and less C-conformant ways of casting your callback type
-have been omitted....</p>
+instead have been omitted.</p>
+<p>Another common scenario is having some data structure with multiple
+watchers:</p>
+<pre>  struct my_biggy
+  {
+    int some_data;
+    ev_timer t1;
+    ev_timer t2;
+  }
+</pre>
+<p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated,
+you need to use <code>offsetof</code>:</p>
+<pre>  #include &lt;stddef.h&gt;
+  static void
+  t1_cb (EV_P_ struct ev_timer *w, int revents)
+  {
+    struct my_biggy big = (struct my_biggy *
+      (((char *)w) - offsetof (struct my_biggy, t1));
+  }
+  static void
+  t2_cb (EV_P_ struct ev_timer *w, int revents)
+  {
+    struct my_biggy big = (struct my_biggy *
+      (((char *)w) - offsetof (struct my_biggy, t2));
+  }
+</pre>
 </div>
-<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
 <div id="WATCHER_TYPES_CONTENT">
 <p>This section describes each watcher in detail, but will not repeat
-information given in the last section.</p>
+information given in the last section. Any initialisation/set macros,
+functions and members specific to the watcher type are explained.</p>
+<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
+while the watcher is active, you can look at the member and expect some
+sensible content, but you must not modify it (you can modify it while the
+watcher is stopped to your hearts content), or <i>[read-write]</i>, which
+means you can expect it to have some sensible content while the watcher
+is active, but you can also modify it. Modifying it may not do something
+sensible or take immediate effect (or do anything at all), but libev will
+not crash or malfunction in any way.</p>
 </div>
-<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2>
+<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2>
 <div id="code_ev_io_code_is_this_file_descrip-2">
 <p>I/O watchers check whether a file descriptor is readable or writable
-in each iteration of the event loop (This behaviour is called
+in each iteration of the event loop, or, more precisely, when reading
-level-triggering because you keep receiving events as long as the
+would not block the process and writing would at least be able to write
-condition persists. Remember you can stop the watcher if you don't want to
+some data. This behaviour is called level-triggering because you keep
-act on the event and neither want to receive future events).</p>
+receiving events as long as the condition persists. Remember you can stop
+the watcher if you don't want to act on the event and neither want to
+receive future events.</p>
 <p>In general you can register as many read and/or write event watchers per
 fd as you want (as long as you don't confuse yourself). Setting all file
 descriptors to non-blocking mode is also usually a good idea (but not
 required if you know what you are doing).</p>
 <p>You have to be careful with dup'ed file descriptors, though. Some backends
 (the linux epoll backend is a notable example) cannot handle dup'ed file
 descriptors correctly if you register interest in two or more fds pointing
-to the same underlying file/socket etc. description (that is, they share
+to the same underlying file/socket/etc. description (that is, they share
 the same underlying &quot;file open&quot;).</p>
 <p>If you must do this, then force the use of a known-to-be-good backend
 (at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
 <code>EVBACKEND_POLL</code>).</p>
+<p>Another thing you have to watch out for is that it is quite easy to
+receive &quot;spurious&quot; readyness notifications, that is your callback might
+be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block
+because there is no data. Not only are some backends known to create a
+lot of those (for example solaris ports), it is very easy to get into
+this situation even with a relatively standard program structure. Thus
+it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
+<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
+<p>If you cannot run the fd in non-blocking mode (for example you should not
+play around with an Xlib connection), then you have to seperately re-test
+whether a file descriptor is really ready with a known-to-be good interface
+such as poll (fortunately in our Xlib example, Xlib already does this on
+its own, so its quite safe to use).</p>
 <dl>
 	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
 	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
 	<dd>
-		<p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive
+		<p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
-events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ |
+rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
-EV_WRITE</code> to receive the given events.</p>
+<code>EV_READ | EV_WRITE</code> to receive the given events.</p>
-		<p>Please note that most of the more scalable backend mechanisms (for example
+	</dd>
-epoll and solaris ports) can result in spurious readyness notifications
+	<dt>int fd [read-only]</dt>
-for file descriptors, so you practically need to use non-blocking I/O (and
+	<dd>
-treat callback invocation as hint only), or retest separately with a safe
+		<p>The file descriptor being watched.</p>
-interface before doing I/O (XLib can do this), or force the use of either
+	</dd>
-<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this
+	<dt>int events [read-only]</dt>
-problem. Also note that it is quite easy to have your callback invoked
+	<dd>
-when the readyness condition is no longer valid even when employing
+		<p>The events being watched.</p>
-typical ways of handling events, so its a good idea to use non-blocking
-I/O unconditionally.</p>
 	</dd>
 </dl>
-<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
+<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
 readable, but only once. Since it is likely line-buffered, you could
-attempt to read a whole line in the callback:</p>
+attempt to read a whole line in the callback.</p>
 <pre>  static void
   stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
   {
      ev_io_stop (loop, w);
     .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors
 </pre>
 </div>
-<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2>
+<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2>
 <div id="code_ev_timer_code_relative_and_opti-2">
 <p>Timer watchers are simple relative timers that generate an event after a
 given time, and optionally repeating in regular intervals after that.</p>
 <p>The timers are based on real time, that is, if you register an event that
 times out after an hour and you reset your system clock to last years
 	</dd>
 	<dt>ev_timer_again (loop)</dt>
 	<dd>
 		<p>This will act as if the timer timed out and restart it again if it is
 repeating. The exact semantics are:</p>
+		<p>If the timer is pending, its pending status is cleared.</p>
-		<p>If the timer is started but nonrepeating, stop it.</p>
+		<p>If the timer is started but nonrepeating, stop it (as if it timed out).</p>
-		<p>If the timer is repeating, either start it if necessary (with the repeat
+		<p>If the timer is repeating, either start it if necessary (with the
-value), or reset the running timer to the repeat value.</p>
+<code>repeat</code> value), or reset the running timer to the <code>repeat</code> value.</p>
 		<p>This sounds a bit complicated, but here is a useful and typical
 example: Imagine you have a tcp connection and you want a so-called idle
 timeout, that is, you want to be called when there have been, say, 60
 seconds of inactivity on the socket. The easiest way to do this is to
-configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each
+configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call
-time you successfully read or write some data. If you go into an idle
+<code>ev_timer_again</code> each time you successfully read or write some data. If
-state where you do not expect data to travel on the socket, you can stop
+you go into an idle state where you do not expect data to travel on the
+socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will
-the timer, and again will automatically restart it if need be.</p>
+automatically restart it if need be.</p>
+		<p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code>
+altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p>
+<pre>   ev_timer_init (timer, callback, 0., 5.);
+   ev_timer_again (loop, timer);
+   ...
+   timer-&gt;again = 17.;
+   ev_timer_again (loop, timer);
+   ...
+   timer-&gt;again = 10.;
+   ev_timer_again (loop, timer);
+</pre>
+		<p>This is more slightly efficient then stopping/starting the timer each time
+you want to modify its timeout value.</p>
+	</dd>
+	<dt>ev_tstamp repeat [read-write]</dt>
+	<dd>
+		<p>The current <code>repeat</code> value. Will be used each time the watcher times out
+or <code>ev_timer_again</code> is called and determines the next timeout (if any),
+which is also when any modifications are taken into account.</p>
 	</dd>
 </dl>
-<p>Example: create a timer that fires after 60 seconds.</p>
+<p>Example: Create a timer that fires after 60 seconds.</p>
 <pre>  static void
   one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
   {
     .. one minute over, w is actually stopped right here
   }
   struct ev_timer mytimer;
   ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.);
   ev_timer_start (loop, &amp;mytimer);
 </pre>
-<p>Example: create a timeout timer that times out after 10 seconds of
+<p>Example: Create a timeout timer that times out after 10 seconds of
 inactivity.</p>
 <pre>  static void
   timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
   {
     .. ten seconds without any activity
 </pre>
 </div>
-<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2>
+<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2>
 <div id="code_ev_periodic_code_to_cron_or_not-2">
 <p>Periodic watchers are also timers of a kind, but they are very versatile
 (and unfortunately a bit complex).</p>
 <p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)
 but on wallclock time (absolute time). You can tell a periodic watcher
 to trigger &quot;at&quot; some specific point in time. For example, if you tell a
 periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()
 + 10.</code>) and then reset your system clock to the last year, then it will
 take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger
-roughly 10 seconds later and of course not if you reset your system time
+roughly 10 seconds later).</p>
-again).</p>
 <p>They can also be used to implement vastly more complex timers, such as
-triggering an event on eahc midnight, local time.</p>
+triggering an event on each midnight, local time or other, complicated,
+rules.</p>
 <p>As with timers, the callback is guarenteed to be invoked only when the
 time (<code>at</code>) has been passed, but if multiple periodic timers become ready
 during the same loop iteration then order of execution is undefined.</p>
 <dl>
 	<dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt>
 	<dd>
 		<p>Lots of arguments, lets sort it out... There are basically three modes of
 operation, and we will explain them from simplest to complex:</p>
 		<p>
 			<dl>
-				<dt>* absolute timer (interval = reschedule_cb = 0)</dt>
+				<dt>* absolute timer (at = time, interval = reschedule_cb = 0)</dt>
 				<dd>
 					<p>In this configuration the watcher triggers an event at the wallclock time
 <code>at</code> and doesn't repeat. It will not adjust when a time jump occurs,
 that is, if it is to be run at January 1st 2011 then it will run when the
 system time reaches or surpasses this time.</p>
 				</dd>
-				<dt>* non-repeating interval timer (interval &gt; 0, reschedule_cb = 0)</dt>
+				<dt>* non-repeating interval timer (at = offset, interval &gt; 0, reschedule_cb = 0)</dt>
 				<dd>
 					<p>In this mode the watcher will always be scheduled to time out at the next
-<code>at + N * interval</code> time (for some integer N) and then repeat, regardless
+<code>at + N * interval</code> time (for some integer N, which can also be negative)
-of any time jumps.</p>
+and then repeat, regardless of any time jumps.</p>
 					<p>This can be used to create timers that do not drift with respect to system
 time:</p>
 <pre>   ev_periodic_set (&amp;periodic, 0., 3600., 0);
 </pre>
 full hour (UTC), or more correctly, when the system time is evenly divisible
 by 3600.</p>
 					<p>Another way to think about it (for the mathematically inclined) is that
 <code>ev_periodic</code> will try to run the callback in this mode at the next possible
 time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p>
+					<p>For numerical stability it is preferable that the <code>at</code> value is near
+<code>ev_now ()</code> (the current time), but there is no range requirement for
+this value.</p>
 				</dd>
-				<dt>* manual reschedule mode (reschedule_cb = callback)</dt>
+				<dt>* manual reschedule mode (at and interval ignored, reschedule_cb = callback)</dt>
 				<dd>
 					<p>In this mode the values for <code>interval</code> and <code>at</code> are both being
 ignored. Instead, each time the periodic watcher gets scheduled, the
 reschedule callback will be called with the watcher as first, and the
 current time as second argument.</p>
 					<p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher,
 ever, or make any event loop modifications</i>. If you need to stop it,
 return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by
-starting a prepare watcher).</p>
+starting an <code>ev_prepare</code> watcher, which is legal).</p>
 					<p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
 ev_tstamp now)</code>, e.g.:</p>
 <pre>   static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
    {
      return now + 60.;
 		<p>Simply stops and restarts the periodic watcher again. This is only useful
 when you changed some parameters or the reschedule callback would return
 a different time than the last time it was called (e.g. in a crond like
 program when the crontabs have changed).</p>
 	</dd>
+	<dt>ev_tstamp offset [read-write]</dt>
+	<dd>
+		<p>When repeating, this contains the offset value, otherwise this is the
+absolute point in time (the <code>at</code> value passed to <code>ev_periodic_set</code>).</p>
+		<p>Can be modified any time, but changes only take effect when the periodic
+timer fires or <code>ev_periodic_again</code> is being called.</p>
+	</dd>
+	<dt>ev_tstamp interval [read-write]</dt>
+	<dd>
+		<p>The current interval value. Can be modified any time, but changes only
+take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
+called.</p>
+	</dd>
+	<dt>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]</dt>
+	<dd>
+		<p>The current reschedule callback, or <code>0</code>, if this functionality is
+switched off. Can be changed any time, but changes only take effect when
+the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
+	</dd>
 </dl>
-<p>Example: call a callback every hour, or, more precisely, whenever the
+<p>Example: Call a callback every hour, or, more precisely, whenever the
 system clock is divisible by 3600. The callback invocation times have
 potentially a lot of jittering, but good long-term stability.</p>
 <pre>  static void
   clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
   {
   struct ev_periodic hourly_tick;
   ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0);
   ev_periodic_start (loop, &amp;hourly_tick);
 </pre>
-<p>Example: the same as above, but use a reschedule callback to do it:</p>
+<p>Example: The same as above, but use a reschedule callback to do it:</p>
 <pre>  #include &lt;math.h&gt;
   static ev_tstamp
   my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
   {
   }
   ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
 </pre>
-<p>Example: call a callback every hour, starting now:</p>
+<p>Example: Call a callback every hour, starting now:</p>
 <pre>  struct ev_periodic hourly_tick;
   ev_periodic_init (&amp;hourly_tick, clock_cb,
                     fmod (ev_now (loop), 3600.), 3600., 0);
   ev_periodic_start (loop, &amp;hourly_tick);
 </pre>
 </div>
-<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2>
+<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2>
 <div id="code_ev_signal_code_signal_me_when_a-2">
 <p>Signal watchers will trigger an event when the process receives a specific
 signal one or more times. Even though signals are very asynchronous, libev
 will try it's best to deliver signals synchronously, i.e. as part of the
 normal event processing, like any other event.</p>
 	<dt>ev_signal_set (ev_signal *, int signum)</dt>
 	<dd>
 		<p>Configures the watcher to trigger on the given signal number (usually one
 of the <code>SIGxxx</code> constants).</p>
 	</dd>
+	<dt>int signum [read-only]</dt>
+	<dd>
+		<p>The signal the watcher watches out for.</p>
+	</dd>
 </dl>
 </div>
-<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2>
+<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>
-<div id="code_ev_child_code_wait_for_pid_stat-2">
+<div id="code_ev_child_code_watch_out_for_pro-2">
 <p>Child watchers trigger when your process receives a SIGCHLD in response to
 some child status changes (most typically when a child of yours dies).</p>
 <dl>
 	<dt>ev_child_init (ev_child *, callback, int pid)</dt>
 	<dt>ev_child_set (ev_child *, int pid)</dt>
 at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see
 the status word (use the macros from <code>sys/wait.h</code> and see your systems
 <code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
 process causing the status change.</p>
 	</dd>
+	<dt>int pid [read-only]</dt>
+	<dd>
+		<p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p>
+	</dd>
+	<dt>int rpid [read-write]</dt>
+	<dd>
+		<p>The process id that detected a status change.</p>
+	</dd>
+	<dt>int rstatus [read-write]</dt>
+	<dd>
+		<p>The process exit/trace status caused by <code>rpid</code> (see your systems
+<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
+	</dd>
 </dl>
-<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>
+<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
 <pre>  static void
   sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
   {
     ev_unloop (loop, EVUNLOOP_ALL);
   }
 </pre>
 </div>
+<h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2>
+<div id="code_ev_stat_code_did_the_file_attri-2">
+<p>This watches a filesystem path for attribute changes. That is, it calls
+<code>stat</code> regularly (or when the OS says it changed) and sees if it changed
+compared to the last time, invoking the callback if it did.</p>
+<p>The path does not need to exist: changing from &quot;path exists&quot; to &quot;path does
+not exist&quot; is a status change like any other. The condition &quot;path does
+not exist&quot; is signified by the <code>st_nlink</code> field being zero (which is
+otherwise always forced to be at least one) and all the other fields of
+the stat buffer having unspecified contents.</p>
+<p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is
+relative and your working directory changes, the behaviour is undefined.</p>
+<p>Since there is no standard to do this, the portable implementation simply
+calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You
+can specify a recommended polling interval for this case. If you specify
+a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
+unspecified default</i> value will be used (which you can expect to be around
+five seconds, although this might change dynamically). Libev will also
+impose a minimum interval which is currently around <code>0.1</code>, but thats
+usually overkill.</p>
+<p>This watcher type is not meant for massive numbers of stat watchers,
+as even with OS-supported change notifications, this can be
+resource-intensive.</p>
+<p>At the time of this writing, only the Linux inotify interface is
+implemented (implementing kqueue support is left as an exercise for the
+reader). Inotify will be used to give hints only and should not change the
+semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs
+to fall back to regular polling again even with inotify, but changes are
+usually detected immediately, and if the file exists there will be no
+polling.</p>
+<dl>
+	<dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt>
+	<dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt>
+	<dd>
+		<p>Configures the watcher to wait for status changes of the given
+<code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to
+be detected and should normally be specified as <code>0</code> to let libev choose
+a suitable value. The memory pointed to by <code>path</code> must point to the same
+path for as long as the watcher is active.</p>
+		<p>The callback will be receive <code>EV_STAT</code> when a change was detected,
+relative to the attributes at the time the watcher was started (or the
+last change was detected).</p>
+	</dd>
+	<dt>ev_stat_stat (ev_stat *)</dt>
+	<dd>
+		<p>Updates the stat buffer immediately with new values. If you change the
+watched path in your callback, you could call this fucntion to avoid
+detecting this change (while introducing a race condition). Can also be
+useful simply to find out the new values.</p>
+	</dd>
+	<dt>ev_statdata attr [read-only]</dt>
+	<dd>
+		<p>The most-recently detected attributes of the file. Although the type is of
+<code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types
+suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there
+was some error while <code>stat</code>ing the file.</p>
+	</dd>
+	<dt>ev_statdata prev [read-only]</dt>
+	<dd>
+		<p>The previous attributes of the file. The callback gets invoked whenever
+<code>prev</code> != <code>attr</code>.</p>
+	</dd>
+	<dt>ev_tstamp interval [read-only]</dt>
+	<dd>
+		<p>The specified interval.</p>
+	</dd>
+	<dt>const char *path [read-only]</dt>
+	<dd>
+		<p>The filesystem path that is being watched.</p>
+	</dd>
+</dl>
+<p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p>
+<pre>  static void
+  passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
+  {
+    /* /etc/passwd changed in some way */
+    if (w-&gt;attr.st_nlink)
+      {
+        printf (&quot;passwd current size  %ld\n&quot;, (long)w-&gt;attr.st_size);
+        printf (&quot;passwd current atime %ld\n&quot;, (long)w-&gt;attr.st_mtime);
+        printf (&quot;passwd current mtime %ld\n&quot;, (long)w-&gt;attr.st_mtime);
+      }
+    else
+      /* you shalt not abuse printf for puts */
+      puts (&quot;wow, /etc/passwd is not there, expect problems. &quot;
+            &quot;if this is windows, they already arrived\n&quot;);
+  }
+  ...
+  ev_stat passwd;
+  ev_stat_init (&amp;passwd, passwd_cb, &quot;/etc/passwd&quot;);
+  ev_stat_start (loop, &amp;passwd);
+</pre>
+</div>
-<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2>
+<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>
 <div id="code_ev_idle_code_when_you_ve_got_no-2">
-<p>Idle watchers trigger events when there are no other events are pending
+<p>Idle watchers trigger events when no other events of the same or higher
-(prepare, check and other idle watchers do not count). That is, as long
+priority are pending (prepare, check and other idle watchers do not
-as your process is busy handling sockets or timeouts (or even signals,
+count).</p>
-imagine) it will not be triggered. But when your process is idle all idle
+<p>That is, as long as your process is busy handling sockets or timeouts
-watchers are being called again and again, once per event loop iteration -
+(or even signals, imagine) of the same or higher priority it will not be
+triggered. But when your process is idle (or only lower-priority watchers
+are pending), the idle watchers are being called once per event loop
-until stopped, that is, or your process receives more events and becomes
+iteration - until stopped, that is, or your process receives more events
-busy.</p>
+and becomes busy again with higher priority stuff.</p>
 <p>The most noteworthy effect is that as long as any idle watchers are
 active, the process will not block when waiting for new events.</p>
 <p>Apart from keeping your process non-blocking (which is a useful
 effect on its own sometimes), idle watchers are a good place to do
 &quot;pseudo-background processing&quot;, or delay processing stuff to after the
 		<p>Initialises and configures the idle watcher - it has no parameters of any
 kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
 believe me.</p>
 	</dd>
 </dl>
-<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the
+<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
-callback, free it. Alos, use no error checking, as usual.</p>
+callback, free it. Also, use no error checking, as usual.</p>
 <pre>  static void
   idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
   {
     free (w);
     // now do something you wanted to do when the program has
 </pre>
 </div>
-<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2>
+<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2>
 <div id="code_ev_prepare_code_and_code_ev_che-2">
 <p>Prepare and check watchers are usually (but not always) used in tandem:
 prepare watchers get invoked before the process blocks and check watchers
 afterwards.</p>
+<p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter
+the current event loop from either <code>ev_prepare</code> or <code>ev_check</code>
+watchers. Other loops than the current one are fine, however. The
+rationale behind this is that you do not need to check for recursion in
+those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking,
+<code>ev_check</code> so if you have one watcher of each kind they will always be
+called in pairs bracketing the blocking call.</p>
 <p>Their main purpose is to integrate other event mechanisms into libev and
 their use is somewhat advanced. This could be used, for example, to track
 variable changes, implement your own watchers, integrate net-snmp or a
-coroutine library and lots more.</p>
+coroutine library and lots more. They are also occasionally useful if
+you cache some data and want to flush it before blocking (for example,
+in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code>
+watcher).</p>
 <p>This is done by examining in each prepare call which file descriptors need
 to be watched by the other library, registering <code>ev_io</code> watchers for
 them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
 provide just this functionality). Then, in the check watcher you check for
 any events that occured (by checking the pending status of all watchers
 are ready to run (it's actually more complicated: it only runs coroutines
 with priority higher than or equal to the event loop and one coroutine
 of lower priority, but only once, using idle watchers to keep the event
 loop from blocking if lower-priority coroutines are active, thus mapping
 low-priority coroutines to idle/background tasks).</p>
+<p>It is recommended to give <code>ev_check</code> watchers highest (<code>EV_MAXPRI</code>)
+priority, to ensure that they are being run before any other watchers
+after the poll. Also, <code>ev_check</code> watchers (and <code>ev_prepare</code> watchers,
+too) should not activate (&quot;feed&quot;) events into libev. While libev fully
+supports this, they will be called before other <code>ev_check</code> watchers did
+their job. As <code>ev_check</code> watchers are often used to embed other event
+loops those other event loops might be in an unusable state until their
+<code>ev_check</code> watcher ran (always remind yourself to coexist peacefully with
+others).</p>
 <dl>
 	<dt>ev_prepare_init (ev_prepare *, callback)</dt>
 	<dt>ev_check_init (ev_check *, callback)</dt>
 	<dd>
 		<p>Initialises and configures the prepare or check watcher - they have no
 parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
 macros, but using them is utterly, utterly and completely pointless.</p>
 	</dd>
 </dl>
-<p>Example: *TODO*.</p>
+<p>There are a number of principal ways to embed other event loops or modules
+into libev. Here are some ideas on how to include libadns into libev
+(there is a Perl module named <code>EV::ADNS</code> that does this, which you could
+use for an actually working example. Another Perl module named <code>EV::Glib</code>
+embeds a Glib main context into libev, and finally, <code>Glib::EV</code> embeds EV
+into the Glib event loop).</p>
+<p>Method 1: Add IO watchers and a timeout watcher in a prepare handler,
+and in a check watcher, destroy them and call into libadns. What follows
+is pseudo-code only of course. This requires you to either use a low
+priority for the check watcher or use <code>ev_clear_pending</code> explicitly, as
+the callbacks for the IO/timeout watchers might not have been called yet.</p>
+<pre>  static ev_io iow [nfd];
+  static ev_timer tw;
+  static void
+  io_cb (ev_loop *loop, ev_io *w, int revents)
+  {
+  }
+  // create io watchers for each fd and a timer before blocking
+  static void
+  adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
+  {
+    int timeout = 3600000;
+    struct pollfd fds [nfd];
+    // actual code will need to loop here and realloc etc.
+    adns_beforepoll (ads, fds, &amp;nfd, &amp;timeout, timeval_from (ev_time ()));
+    /* the callback is illegal, but won't be called as we stop during check */
+    ev_timer_init (&amp;tw, 0, timeout * 1e-3);
+    ev_timer_start (loop, &amp;tw);
+    // create one ev_io per pollfd
+    for (int i = 0; i &lt; nfd; ++i)
+      {
+        ev_io_init (iow + i, io_cb, fds [i].fd,
+          ((fds [i].events &amp; POLLIN ? EV_READ : 0)
+           | (fds [i].events &amp; POLLOUT ? EV_WRITE : 0)));
+        fds [i].revents = 0;
+        ev_io_start (loop, iow + i);
+      }
+  }
+  // stop all watchers after blocking
+  static void
+  adns_check_cb (ev_loop *loop, ev_check *w, int revents)
+  {
+    ev_timer_stop (loop, &amp;tw);
+    for (int i = 0; i &lt; nfd; ++i)
+      {
+        // set the relevant poll flags
+        // could also call adns_processreadable etc. here
+        struct pollfd *fd = fds + i;
+        int revents = ev_clear_pending (iow + i);
+        if (revents &amp; EV_READ ) fd-&gt;revents |= fd-&gt;events &amp; POLLIN;
+        if (revents &amp; EV_WRITE) fd-&gt;revents |= fd-&gt;events &amp; POLLOUT;
+        // now stop the watcher
+        ev_io_stop (loop, iow + i);
+      }
+    adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
+  }
+</pre>
+<p>Method 2: This would be just like method 1, but you run <code>adns_afterpoll</code>
+in the prepare watcher and would dispose of the check watcher.</p>
+<p>Method 3: If the module to be embedded supports explicit event
+notification (adns does), you can also make use of the actual watcher
+callbacks, and only destroy/create the watchers in the prepare watcher.</p>
+<pre>  static void
+  timer_cb (EV_P_ ev_timer *w, int revents)
+  {
+    adns_state ads = (adns_state)w-&gt;data;
+    update_now (EV_A);
+    adns_processtimeouts (ads, &amp;tv_now);
+  }
+  static void
+  io_cb (EV_P_ ev_io *w, int revents)
+  {
+    adns_state ads = (adns_state)w-&gt;data;
+    update_now (EV_A);
+    if (revents &amp; EV_READ ) adns_processreadable  (ads, w-&gt;fd, &amp;tv_now);
+    if (revents &amp; EV_WRITE) adns_processwriteable (ads, w-&gt;fd, &amp;tv_now);
+  }
+  // do not ever call adns_afterpoll
+</pre>
+<p>Method 4: Do not use a prepare or check watcher because the module you
+want to embed is too inflexible to support it. Instead, youc na override
+their poll function.  The drawback with this solution is that the main
+loop is now no longer controllable by EV. The <code>Glib::EV</code> module does
+this.</p>
+<pre>  static gint
+  event_poll_func (GPollFD *fds, guint nfds, gint timeout)
+  {
+    int got_events = 0;
+    for (n = 0; n &lt; nfds; ++n)
+      // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
+    if (timeout &gt;= 0)
+      // create/start timer
+    // poll
+    ev_loop (EV_A_ 0);
+    // stop timer again
+    if (timeout &gt;= 0)
+      ev_timer_stop (EV_A_ &amp;to);
+    // stop io watchers again - their callbacks should have set
+    for (n = 0; n &lt; nfds; ++n)
+      ev_io_stop (EV_A_ iow [n]);
+    return got_events;
+  }
+</pre>
 </div>
-<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2>
+<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>
 <div id="code_ev_embed_code_when_one_backend_-2">
 <p>This is a rather advanced watcher type that lets you embed one event loop
 into another (currently only <code>ev_io</code> events are supported in the embedded
 loop, other types of watchers might be handled in a delayed or incorrect
 fashion and must not be used).</p>
 	<dd>
 		<p>Make a single, non-blocking sweep over the embedded loop. This works
 similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
 apropriate way for embedded loops.</p>
 	</dd>
+	<dt>struct ev_loop *loop [read-only]</dt>
+	<dd>
+		<p>The embedded event loop.</p>
+	</dd>
 </dl>
 </div>
-<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h2 id="code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</h2>
+<div id="code_ev_fork_code_the_audacity_to_re-2">
+<p>Fork watchers are called when a <code>fork ()</code> was detected (usually because
+whoever is a good citizen cared to tell libev about it by calling
+<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
+event loop blocks next and before <code>ev_check</code> watchers are being called,
+and only in the child after the fork. If whoever good citizen calling
+<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
+handlers will be invoked, too, of course.</p>
+<dl>
+	<dt>ev_fork_init (ev_signal *, callback)</dt>
+	<dd>
+		<p>Initialises and configures the fork watcher - it has no parameters of any
+kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,
+believe me.</p>
+	</dd>
+</dl>
+</div>
+<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
 <div id="OTHER_FUNCTIONS_CONTENT">
 <p>There are some other functions of possible interest. Described. Here. Now.</p>
 <dl>
 	<dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
 	<dd>
 </div>
-<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
 <div id="LIBEVENT_EMULATION_CONTENT">
 <p>Libev offers a compatibility emulation layer for libevent. It cannot
 emulate the internals of libevent, so here are some usage hints:</p>
 <dl>
 	<dt>* Use it by including &lt;event.h&gt;, as usual.</dt>
 	<dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
 to use the libev header file and library.</dt>
 </dl>
 </div>
-<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="C_SUPPORT">C++ SUPPORT</h1>
 <div id="C_SUPPORT_CONTENT">
 <p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
 you to use some convinience methods to start/stop watchers and also change
 the callback model to a model using method callbacks on objects.</p>
 <p>To use it,</p>
 <pre>  #include &lt;ev++.h&gt;
 </pre>
-<p>(it is not installed by default). This automatically includes <cite>ev.h</cite>
+<p>This automatically includes <cite>ev.h</cite> and puts all of its definitions (many
-and puts all of its definitions (many of them macros) into the global
+of them macros) into the global namespace. All C++ specific things are
-namespace. All C++ specific things are put into the <code>ev</code> namespace.</p>
+put into the <code>ev</code> namespace. It should support all the same embedding
-<p>It should support all the same embedding options as <cite>ev.h</cite>, most notably
+options as <cite>ev.h</cite>, most notably <code>EV_MULTIPLICITY</code>.</p>
-<code>EV_MULTIPLICITY</code>.</p>
+<p>Care has been taken to keep the overhead low. The only data member the C++
+classes add (compared to plain C-style watchers) is the event loop pointer
+that the watcher is associated with (or no additional members at all if
+you disable <code>EV_MULTIPLICITY</code> when embedding libev).</p>
+<p>Currently, functions, and static and non-static member functions can be
+used as callbacks. Other types should be easy to add as long as they only
+need one additional pointer for context. If you need support for other
+types of functors please contact the author (preferably after implementing
+it).</p>
 <p>Here is a list of things available in the <code>ev</code> namespace:</p>
 <dl>
 	<dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
 	<dd>
 		<p>These are just enum values with the same values as the <code>EV_READ</code> etc.
 which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
 defines by many implementations.</p>
 		<p>All of those classes have these methods:</p>
 		<p>
 			<dl>
-				<dt>ev::TYPE::TYPE (object *, object::method *)</dt>
+				<dt>ev::TYPE::TYPE ()</dt>
-				<dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt>
+				<dt>ev::TYPE::TYPE (struct ev_loop *)</dt>
 				<dt>ev::TYPE::~TYPE</dt>
 				<dd>
-					<p>The constructor takes a pointer to an object and a method pointer to
+					<p>The constructor (optionally) takes an event loop to associate the watcher
-the event handler callback to call in this class. The constructor calls
+with. If it is omitted, it will use <code>EV_DEFAULT</code>.</p>
-<code>ev_init</code> for you, which means you have to call the <code>set</code> method
+					<p>The constructor calls <code>ev_init</code> for you, which means you have to call the
-before starting it. If you do not specify a loop then the constructor
+<code>set</code> method before starting it.</p>
-automatically associates the default loop with this watcher.</p>
+					<p>It will not set a callback, however: You have to call the templated <code>set</code>
+method to set a callback before you can start the watcher.</p>
+					<p>(The reason why you have to use a method is a limitation in C++ which does
+not allow explicit template arguments for constructors).</p>
 					<p>The destructor automatically stops the watcher if it is active.</p>
+				</dd>
+				<dt>w-&gt;set&lt;class, &amp;class::method&gt; (object *)</dt>
+				<dd>
+					<p>This method sets the callback method to call. The method has to have a
+signature of <code>void (*)(ev_TYPE &amp;, int)</code>, it receives the watcher as
+first argument and the <code>revents</code> as second. The object must be given as
+parameter and is stored in the <code>data</code> member of the watcher.</p>
+					<p>This method synthesizes efficient thunking code to call your method from
+the C callback that libev requires. If your compiler can inline your
+callback (i.e. it is visible to it at the place of the <code>set</code> call and
+your compiler is good :), then the method will be fully inlined into the
+thunking function, making it as fast as a direct C callback.</p>
+					<p>Example: simple class declaration and watcher initialisation</p>
+<pre>  struct myclass
+  {
+    void io_cb (ev::io &amp;w, int revents) { }
+  }
+  myclass obj;
+  ev::io iow;
+  iow.set &lt;myclass, &amp;myclass::io_cb&gt; (&amp;obj);
+</pre>
+				</dd>
+				<dt>w-&gt;set&lt;function&gt; (void *data = 0)</dt>
+				<dd>
+					<p>Also sets a callback, but uses a static method or plain function as
+callback. The optional <code>data</code> argument will be stored in the watcher's
+<code>data</code> member and is free for you to use.</p>
+					<p>The prototype of the <code>function</code> must be <code>void (*)(ev::TYPE &amp;w, int)</code>.</p>
+					<p>See the method-<code>set</code> above for more details.</p>
+					<p>Example:</p>
+<pre>  static void io_cb (ev::io &amp;w, int revents) { }
+  iow.set &lt;io_cb&gt; ();
+</pre>
 				</dd>
 				<dt>w-&gt;set (struct ev_loop *)</dt>
 				<dd>
 					<p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
 do this when the watcher is inactive (and not pending either).</p>
 				</dd>
 				<dt>w-&gt;set ([args])</dt>
 				<dd>
 					<p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
-called at least once.  Unlike the C counterpart, an active watcher gets
+called at least once. Unlike the C counterpart, an active watcher gets
-automatically stopped and restarted.</p>
+automatically stopped and restarted when reconfiguring it with this
+method.</p>
 				</dd>
 				<dt>w-&gt;start ()</dt>
 				<dd>
-					<p>Starts the watcher. Note that there is no <code>loop</code> argument as the
+					<p>Starts the watcher. Note that there is no <code>loop</code> argument, as the
-constructor already takes the loop.</p>
+constructor already stores the event loop.</p>
 				</dd>
 				<dt>w-&gt;stop ()</dt>
 				<dd>
 					<p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
 				</dd>
 <code>ev_TYPE_again</code> function.</p>
 				</dd>
 				<dt>w-&gt;sweep ()       <code>ev::embed</code> only</dt>
 				<dd>
 					<p>Invokes <code>ev_embed_sweep</code>.</p>
+				</dd>
+				<dt>w-&gt;update ()      <code>ev::stat</code> only</dt>
+				<dd>
+					<p>Invokes <code>ev_stat_stat</code>.</p>
 				</dd>
 			</dl>
 		</p>
 	</dd>
 </dl>
     myclass ();
   }
   myclass::myclass (int fd)
-  : io   (this, &amp;myclass::io_cb),
-    idle (this, &amp;myclass::idle_cb)
   {
+    io  .set &lt;myclass, &amp;myclass::io_cb  &gt; (this);
+    idle.set &lt;myclass, &amp;myclass::idle_cb&gt; (this);
     io.start (fd, ev::READ);
   }
-</pre>
+</pre>
 </div>
-<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
+<div id="MACRO_MAGIC_CONTENT">
+<p>Libev can be compiled with a variety of options, the most fundemantal is
+<code>EV_MULTIPLICITY</code>. This option determines whether (most) functions and
+callbacks have an initial <code>struct ev_loop *</code> argument.</p>
+<p>To make it easier to write programs that cope with either variant, the
+following macros are defined:</p>
+<dl>
+	<dt><code>EV_A</code>, <code>EV_A_</code></dt>
+	<dd>
+		<p>This provides the loop <i>argument</i> for functions, if one is required (&quot;ev
+loop argument&quot;). The <code>EV_A</code> form is used when this is the sole argument,
+<code>EV_A_</code> is used when other arguments are following. Example:</p>
+<pre>  ev_unref (EV_A);
+  ev_timer_add (EV_A_ watcher);
+  ev_loop (EV_A_ 0);
+</pre>
+		<p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope,
+which is often provided by the following macro.</p>
+	</dd>
+	<dt><code>EV_P</code>, <code>EV_P_</code></dt>
+	<dd>
+		<p>This provides the loop <i>parameter</i> for functions, if one is required (&quot;ev
+loop parameter&quot;). The <code>EV_P</code> form is used when this is the sole parameter,
+<code>EV_P_</code> is used when other parameters are following. Example:</p>
+<pre>  // this is how ev_unref is being declared
+  static void ev_unref (EV_P);
+  // this is how you can declare your typical callback
+  static void cb (EV_P_ ev_timer *w, int revents)
+</pre>
+		<p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite
+suitable for use with <code>EV_A</code>.</p>
+	</dd>
+	<dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt>
+	<dd>
+		<p>Similar to the other two macros, this gives you the value of the default
+loop, if multiple loops are supported (&quot;ev loop default&quot;).</p>
+	</dd>
+</dl>
+<p>Example: Declare and initialise a check watcher, utilising the above
+macros so it will work regardless of whether multiple loops are supported
+or not.</p>
+<pre>  static void
+  check_cb (EV_P_ ev_timer *w, int revents)
+  {
+    ev_check_stop (EV_A_ w);
+  }
+  ev_check check;
+  ev_check_init (&amp;check, check_cb);
+  ev_check_start (EV_DEFAULT_ &amp;check);
+  ev_loop (EV_DEFAULT_ 0);
+</pre>
+</div>
+<h1 id="EMBEDDING">EMBEDDING</h1>
 <div id="EMBEDDING_CONTENT">
 <p>Libev can (and often is) directly embedded into host
 applications. Examples of applications that embed it include the Deliantra
 Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
 and rxvt-unicode.</p>
   ev_vars.h
   ev_wrap.h
   ev_win32.c      required on win32 platforms only
-  ev_select.c     only when select backend is enabled (which is is by default)
+  ev_select.c     only when select backend is enabled (which is enabled by default)
   ev_poll.c       only when poll backend is enabled (disabled by default)
   ev_epoll.c      only when the epoll backend is enabled (disabled by default)
   ev_kqueue.c     only when the kqueue backend is enabled (disabled by default)
   ev_port.c       only when the solaris port backend is enabled (disabled by default)
 </pre>
 <p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
-to compile a single file.</p>
+to compile this single file.</p>
 </div>
 <h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
 <div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
 <p>To include the libevent compatibility API, also include:</p>
 </div>
 <h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
 <div id="AUTOCONF_SUPPORT_CONTENT">
 <p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in
 whatever way you want, you can also <code>m4_include([libev.m4])</code> in your
-<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> off. <cite>ev.c</cite> will then include
+<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then
-<cite>config.h</cite> and configure itself accordingly.</p>
+include <cite>config.h</cite> and configure itself accordingly.</p>
 <p>For this of course you need the m4 file:</p>
 <pre>  libev.m4
 </pre>
 otherwise another method will be used as fallback. This is the preferred
 backend for BSD and BSD-like systems, although on most BSDs kqueue only
 supports some types of fds correctly (the only platform we found that
 supports ptys for example was NetBSD), so kqueue might be compiled in, but
 not be used unless explicitly requested. The best way to use it is to find
-out wether kqueue supports your type of fd properly and use an embedded
+out whether kqueue supports your type of fd properly and use an embedded
 kqueue loop.</p>
 	</dd>
 	<dt>EV_USE_PORT</dt>
 	<dd>
 		<p>If defined to be <code>1</code>, libev will compile in support for the Solaris
 backend for Solaris 10 systems.</p>
 	</dd>
 	<dt>EV_USE_DEVPOLL</dt>
 	<dd>
 		<p>reserved for future expansion, works like the USE symbols above.</p>
+	</dd>
+	<dt>EV_USE_INOTIFY</dt>
+	<dd>
+		<p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify
+interface to speed up <code>ev_stat</code> watchers. Its actual availability will
+be detected at runtime.</p>
 	</dd>
 	<dt>EV_H</dt>
 	<dd>
 		<p>The name of the <cite>ev.h</cite> header file used to include it. The default if
 undefined is <code>&lt;ev.h&gt;</code> in <cite>event.h</cite> and <code>&quot;ev.h&quot;</code> in <cite>ev.c</cite>. This
 will have the <code>struct ev_loop *</code> as first argument, and you can create
 additional independent event loops. Otherwise there will be no support
 for multiple event loops and there is no first event loop pointer
 argument. Instead, all functions act on the single default loop.</p>
 	</dd>
-	<dt>EV_PERIODICS</dt>
+	<dt>EV_MINPRI</dt>
+	<dt>EV_MAXPRI</dt>
+	<dd>
+		<p>The range of allowed priorities. <code>EV_MINPRI</code> must be smaller or equal to
+<code>EV_MAXPRI</code>, but otherwise there are no non-obvious limitations. You can
+provide for more priorities by overriding those symbols (usually defined
+to be <code>-2</code> and <code>2</code>, respectively).</p>
+		<p>When doing priority-based operations, libev usually has to linearly search
+all the priorities, so having many of them (hundreds) uses a lot of space
+and time, so using the defaults of five priorities (-2 .. +2) is usually
+fine.</p>
+		<p>If your embedding app does not need any priorities, defining these both to
+<code>0</code> will save some memory and cpu.</p>
-	<dd>
+	</dd>
+	<dt>EV_PERIODIC_ENABLE</dt>
+	<dd>
-		<p>If undefined or defined to be <code>1</code>, then periodic timers are supported,
+		<p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
-otherwise not. This saves a few kb of code.</p>
+defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
+code.</p>
+	</dd>
+	<dt>EV_IDLE_ENABLE</dt>
+	<dd>
+		<p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If
+defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
+code.</p>
+	</dd>
+	<dt>EV_EMBED_ENABLE</dt>
+	<dd>
+		<p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
+defined to be <code>0</code>, then they are not.</p>
+	</dd>
+	<dt>EV_STAT_ENABLE</dt>
+	<dd>
+		<p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
+defined to be <code>0</code>, then they are not.</p>
+	</dd>
+	<dt>EV_FORK_ENABLE</dt>
+	<dd>
+		<p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If
+defined to be <code>0</code>, then they are not.</p>
+	</dd>
+	<dt>EV_MINIMAL</dt>
+	<dd>
+		<p>If you need to shave off some kilobytes of code at the expense of some
+speed, define this symbol to <code>1</code>. Currently only used for gcc to override
+some inlining decisions, saves roughly 30% codesize of amd64.</p>
+	</dd>
+	<dt>EV_PID_HASHSIZE</dt>
+	<dd>
+		<p><code>ev_child</code> watchers use a small hash table to distribute workload by
+pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
+than enough. If you need to manage thousands of children you might want to
+increase this value (<i>must</i> be a power of two).</p>
+	</dd>
+	<dt>EV_INOTIFY_HASHSIZE</dt>
+	<dd>
+		<p><code>ev_staz</code> watchers use a small hash table to distribute workload by
+inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>),
+usually more than enough. If you need to manage thousands of <code>ev_stat</code>
+watchers you might want to increase this value (<i>must</i> be a power of
+two).</p>
 	</dd>
 	<dt>EV_COMMON</dt>
 	<dd>
 		<p>By default, all watchers have a <code>void *data</code> member. By redefining
 this macro to a something else you can include more and other types of
     SV *self; /* contains this struct */  \
     SV *cb_sv, *fh /* note no trailing &quot;;&quot; */
 </pre>
 	</dd>
-	<dt>EV_CB_DECLARE(type)</dt>
+	<dt>EV_CB_DECLARE (type)</dt>
-	<dt>EV_CB_INVOKE(watcher,revents)</dt>
+	<dt>EV_CB_INVOKE (watcher, revents)</dt>
-	<dt>ev_set_cb(ev,cb)</dt>
+	<dt>ev_set_cb (ev, cb)</dt>
 	<dd>
 		<p>Can be used to change the callback member declaration in each watcher,
 and the way callbacks are invoked and set. Must expand to a struct member
 definition and a statement, respectively. See the <cite>ev.v</cite> header file for
 their default definitions. One possible use for overriding these is to
-avoid the ev_loop pointer as first argument in all cases, or to use method
+avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use
-calls instead of plain function calls in C++.</p>
+method calls instead of plain function calls in C++.</p>
 </div>
 <h2 id="EXAMPLES">EXAMPLES</h2>
 <div id="EXAMPLES_CONTENT">
 		<p>For a real-world example of a program the includes libev
 the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
 interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
 will be compiled. It is pretty complex because it provides its own header
 file.</p>
 		<p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
-that everybody includes and which overrides some autoconf choices:</p>
+that everybody includes and which overrides some configure choices:</p>
+<pre>  #define EV_MINIMAL 1
-<pre>  #define EV_USE_POLL 0
+  #define EV_USE_POLL 0
   #define EV_MULTIPLICITY 0
-  #define EV_PERIODICS 0
+  #define EV_PERIODIC_ENABLE 0
+  #define EV_STAT_ENABLE 0
+  #define EV_FORK_ENABLE 0
   #define EV_CONFIG_H &lt;config.h&gt;
+  #define EV_MINPRI 0
+  #define EV_MAXPRI 0
   #include &quot;ev++.h&quot;
 </pre>
 		<p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
 <pre>  #include &quot;ev_cpp.h&quot;
   #include &quot;ev.c&quot;
-</pre>
+</pre>
 </div>
-<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>
+<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
+<div id="COMPLEXITIES_CONTENT">
+		<p>In this section the complexities of (many of) the algorithms used inside
+libev will be explained. For complexity discussions about backends see the
+documentation for <code>ev_default_init</code>.</p>
+		<p>All of the following are about amortised time: If an array needs to be
+extended, libev needs to realloc and move the whole array, but this
+happens asymptotically never with higher number of elements, so O(1) might
+mean it might do a lengthy realloc operation in rare cases, but on average
+it is much faster and asymptotically approaches constant time.</p>
+		<p>
+			<dl>
+				<dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
+				<dd>
+					<p>This means that, when you have a watcher that triggers in one hour and
+there are 100 watchers that would trigger before that then inserting will
+have to skip those 100 watchers.</p>
+				</dd>
+				<dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
+				<dd>
+					<p>That means that for changing a timer costs less than removing/adding them
+as only the relative motion in the event queue has to be paid for.</p>
+				</dd>
+				<dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
+				<dd>
+					<p>These just add the watcher into an array or at the head of a list.
+=item Stopping check/prepare/idle watchers: O(1)</p>
+				</dd>
+				<dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt>
+				<dd>
+					<p>These watchers are stored in lists then need to be walked to find the
+correct watcher to remove. The lists are usually short (you don't usually
+have many watchers waiting for the same fd or signal).</p>
+				</dd>
+				<dt>Finding the next timer per loop iteration: O(1)</dt>
+				<dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
+				<dd>
+					<p>A change means an I/O watcher gets started or stopped, which requires
+libev to recalculate its status (and possibly tell the kernel).</p>
+				</dd>
+				<dt>Activating one watcher: O(1)</dt>
+				<dt>Priority handling: O(number_of_priorities)</dt>
+				<dd>
+					<p>Priorities are implemented by allocating some space for each
+priority. When doing priority-based operations, libev usually has to
+linearly search all the priorities.</p>
+				</dd>
+			</dl>
+		</p>
+</div>
+<h1 id="AUTHOR">AUTHOR</h1>
 <div id="AUTHOR_CONTENT">
 		<p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>
 </div>
 </div></body>

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Revision 1.76 by root, Sun Dec 9 19:47:29 2007 UTC